CA1122908A - Oxidation inhibiting cap for a carbon friction disc - Google Patents
Oxidation inhibiting cap for a carbon friction discInfo
- Publication number
- CA1122908A CA1122908A CA337,961A CA337961A CA1122908A CA 1122908 A CA1122908 A CA 1122908A CA 337961 A CA337961 A CA 337961A CA 1122908 A CA1122908 A CA 1122908A
- Authority
- CA
- Canada
- Prior art keywords
- carbon friction
- cap
- series
- splines
- friction discs
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/02—Braking members; Mounting thereof
- F16D65/12—Discs; Drums for disc brakes
- F16D65/125—Discs; Drums for disc brakes characterised by the material used for the disc body
- F16D65/126—Discs; Drums for disc brakes characterised by the material used for the disc body the material being of low mechanical strength, e.g. carbon, beryllium; Torque transmitting members therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D55/24—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with a plurality of axially-movable discs, lamellae, or pads, pressed from one side towards an axially-located member
- F16D55/26—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with a plurality of axially-movable discs, lamellae, or pads, pressed from one side towards an axially-located member without self-tightening action
- F16D55/36—Brakes with a plurality of rotating discs all lying side by side
- F16D55/40—Brakes with a plurality of rotating discs all lying side by side actuated by a fluid-pressure device arranged in or one the brake
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D2055/0004—Parts or details of disc brakes
- F16D2055/0058—Fully lined, i.e. braking surface extending over the entire disc circumference
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
OXIDATION INHIBITING CAP FOR A CARBON FRICTION DISC
ABSTRACT OF THE DISCLOSURE
A series of cap members for covering the drive splines of a plurality of carbon friction discs in a wheel and brake assembly to protect the carbon from oxidization. Each of the cap members have first and second tabs that project into the root sections on the carbon disc between the drive splines. The first tabs on the series of cap members are connected to adjacent second tabs to form a continuous ring member which protects the carbon friction disc from degradation caused by oxidation.
During a brake application, the carbon friction disc adjacent the cap member engage a portion of the cap member. Thereafter, the cap member and/or the adjacent carbon friction disc are worn away to maintain the oxidation protection after repeated brake applications.
ABSTRACT OF THE DISCLOSURE
A series of cap members for covering the drive splines of a plurality of carbon friction discs in a wheel and brake assembly to protect the carbon from oxidization. Each of the cap members have first and second tabs that project into the root sections on the carbon disc between the drive splines. The first tabs on the series of cap members are connected to adjacent second tabs to form a continuous ring member which protects the carbon friction disc from degradation caused by oxidation.
During a brake application, the carbon friction disc adjacent the cap member engage a portion of the cap member. Thereafter, the cap member and/or the adjacent carbon friction disc are worn away to maintain the oxidation protection after repeated brake applications.
Description
~lZ~9~8 This invention relates to clisc Lrakes, and more particularly to disc brakes of the carbon friction type.
The use of carbon discs as a friction element in aircraft ~heel and brake assemblies have gained acceptance as a way of increasing the payload of an aircraft by reducing the weight of braking systems.
In U.S. Patent No. 3,639,197, it is disclosed how a continuous carbon fiber can provide a carbon disc with the structural unity needed to absorb repeated braking torque. Such carbon friction disc when used in aircraft braking systems often experience thermal conditions above 800F. Above 800F the non-swept areas of the carbon friction disc are subject to accelerated oxidation which can lead to a disintegration of the carbon matrix and continuous carbon fiber resulting in a brake element failure.
In U.S. Patent No. 3,914, 508 a method is disclosed for protecting a carbon substrate in a moist environment from oxidation by coating a selected surface thereof with a boron and metallic mixture attached thereto by a resin matrix. As with most coatings, it is difficult to maintain a uniform thickness over the entire peripheral surface.
As a result where the coating is limited or absent, deterioration of the carbon substrate often takes place after repeated applications.
In a further attempt to protect a carbon friction material, a metal ring as disclosed in U.S. Patent 3,473,637, was placed on the outer periphery of a carbon disc to prevent oxidation of the non-swept area. During frictional operation when the thermal energy produced is low, such protection is effective. However, as the thermal energy generated during braking increases, the unity of the carbon material and steel ring change in a direct proportion to the differences in their thermal coefficients of expansion. After a repeated ~.a - 1 - ~ ~
l~ZZ908 number of frictiona] cnga~ements at high teml)eratures, structural defects can occur along the peripllcry of the carbon material because of different coefficients of expansion. Thereafter, oxygen in the surrounding air can enter and degrade the underlying carbon friction disc.
U.S. Patent 3,9~2,395 discloses a protection member which matches the coefficient of thermal expansion of the carbon friction disc. The protection member, which includes a woven carbon sheath and a protecting screen, is bonded to the peripheral non-swept surface to protect the underlying carbon friction disc. In order to protect the driving slots on the rotor member, a reinforcing plate is attached to the peripheral surface by a driving pin that extends through the carbon friction disc. Unfortunately, the driving pins are located in a high stress area and under some extreme conditions a structural failure may occur in the area of the driving pins.
The present invention resides in a wheel and brake assembly having a key slot coupling through which a plurality of carbon friction discs are moved toward each other during a brake application by an actuator to develop a braking torque, each of the carbon friction dlscs having a series of splines separated by root sectlon, the splines and root sections being protected by cover means to reduce degradation of the carbon friction discs by an oxidizing atmosphere.
In the present invention the cover means extends into the root sections and engage adjacent carbon friction discs on each brake application to maintain the protection after repeated brake applications.
In a specific embodiment of the invention the cover means includes a series of cap members which surround a corresponding series of driving splines to protect the underlying carbon material from degradation through oxidation.
Each of the cap members have a portion thereof that extencl into swept areas of the carbon ~riction disc, and first and second tabs that project into the root sections between the driving splines. The first tab on a cap is fixed to a second tab on an adjacent cap to hold the caps tight against the splines and thereby establisll a continuous ring of protection against oxidation for the carbon friction disc.
During a brake application, the carbon friction disc adjacent the series of cap members engage a portion of each cap member and provide a positive seal from an oxidation atmosphere for the non-swept portion of the carbon friction disc. As the carbon friction discs wear, either that portion of the cap members in the swept area or the adjacent carbon friction discs wear to maintain the positive seal of protection after repeated brake applications.
It is an object of this invention to provide a carbon friction disc in a wheel and brake system with a series of cap members to protect the driving splines and root sections from oxidation during a brake application.
~zz908 It is another object of this invention to provide a carbon frictiGn disc ~ith a series cf ~etal cap members for surrounding a corresponding sertes o~ driving ~lines.
It is a further object of this ;nvention to provide a relatively fle~ible metallic mo~ber for protecting a peripheral surface of a carbon friction disc and thereby reduce the possibility of degradation thereof in an oxidi~ing atmosphere.
These and other obiects should be apparent from reading this specification and viewing the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is 3 sectiona; view of an aircraft wheel and brake assembly having a plurality carbon fr;ction disc with protection caps made according to this invention to reduce degradation of the carbon friction disc when exposed to an oxidizing atmosphere;
Figure 2 is a perspective vie~w of a segment of the carban frlction disc of Figure 1 having protection caps located on the drtving splines;
Figure 3 is a sectional view taken along ltne 3-3 of Figure 2;
Figure 4 is a perspective view of a single protectton cap;
Figure 5 is a sectional view of a segment of a carbon frlction disc taken along lines 5-5 of Figure 2 sho~lng the relationships of a protection cap and the peripheral surface of adjacont carbon friction discs after repeated brake applications;
Fi~ure 6 is a sectional view of a segment of a c~rbon disc having a pro-tection cap wlth an abrasive surface engaged wlth the per;pheral surface of adjacent carbon friction discs; and Figure 7 is a sectlonal vie~ of the carbon friction disc of Fi~ure 6 after a predetermined number of brake applications~
~A
DETAILED DESCfilPTION OF THE I~VENTIC~!
The ~heel and brake assembly showr) In Figure l includes a ~heel lO, only partially sho~n that is rotatably mounted sn a stationary axle 12 and a brake 15 ~hat is m~unted on a stationary carrier member 14 fixed to the axle ll by locating pin 12ain slots 18 and 25, Since the structure For rotatably mounting ~heel l~ to axle 12 an~ fi,~ing the stationary carrier member 14 to the axle 12 is well known, rur~her description thereof is not deemed to be n~cessary.
The wheel 10 has a first section 32 th3t includes a hub 36 and a rim 38 interconnected to each other by a plura!ity of spokes 40 and a secor,d sect;on 34, The first and second sections 32 and 34 are joir,ed tosether by a plurality of bolts 31 after a tire is mour.~ed on the whe~l lO, The carrier member l4 contains a plurality o~ fluid motors 15 (only one is shown in Figure l) which are connected to a fluid pressure scurce ~hrough conduit 23, ach fluid motor 15 has a piston 24 located in a bare 22 that moves a pressure plate 46 toward a backing plate 48 in response to a brake actuation signal in the form of an increase in fluid pressure transmitted through conduit 23 to actuation chamber 30. The back;ng plate 48 ts connected to a flange 42 which radially projects from sleeve 44 which Is secured to the carrier member l4 by a plurality of circumferentially spaced boits 48, The disc brake lllus~rated in Figure l includes a plurality of interleaved rotors 5~, ~shich are splined to and are rotated by the alrcraft wheel 10 and a plurality of statcrs 52, which are splined to sle~e 44 o, the torque tu~e, 80th the rotors and --tators are ~ovable a,xially by piston 24 and are sor~times referred t;a as a brake ~stack~I, rhe pressure plat~ 46, ~hich is attached to piston 24 of the .^lui~ mo.or 16 hasa carbor. friction pad ~;hich acts on and forces the rotors 50 ard statOrs 52 against each other ar.d the entire stack against a carbon ~5-ll'~Z908 friction pad on the backing plate 48~ It is the frictional engagement of the rotatable rotors 50 with the stationary stators 52 which produce the brak;ng actlon of the aircraft ~heel<
Du,ing a brake application, the .emperature generated by the frictional en~agement of the swept sections, illustrated by dashed line 90 in figure 2, of the carbon friction rotors and stators can often reach 500 C.
This temperature wl1ich is carried into the non-swept sections, such as the dr;ving splines 60, 60', 60", and 62, 62', and root sections 71, 71'...71~
separating the splines, could cause the carbon to combine with oxygen n the o air of the surrounding envtronment an~degrade the driving splines. However, a series of cap members 70, 70~...70n, as best shown in ~igures 2 and 4 foFm a continuous rtng of pro.ection for the splines 62 and root section 71 to restrict oxygen from directly contacting the carbon friction rotors and stators 52.
~ ach of the cap members 70 as shown in fjgures 2, 3 and 4 have a base 72 with parallel side walls 74 and 76 and first and second !egs 78 and 80 which extend therefrom. A first tab 82 projects from the ~irst leg 78 and a second tab 84 projects from the seGond leg 80~ The first tab 82 of a first metal cap member 70 is aligned t~ith a second tab 84' of a second cap member 70' and secured together through spot or projection ~elds. Thereafter, the first tab 84' of cap member 70' i5 aligned and welded to the second tab 84" of a me~al cap member 70". This alignment and welding continues until met~i cap member 70n is reached ~ith only the second tab 84 and the first tab 82~
remaining unattached to each other, Thereafter, hase 72 on the first metal cap member 70 is positioned on the top of a spline 62 ~tth tab 84 on leg 80 flush wi~h root section 71. The remaining metal cap member 70~ .,7Qn are positioned on splines 62I...62~ until the f;rst tab 82~ js aligned ~it~ t~e second tah 84 on czp member 7a. As ~hown in Figure 2, tah 82~ laps o~eI the end cf t~b 84 Thereafter, tabs 84 and S2~ can be connected together by a single spot ~eld to establish a continucus ring. ~cwever, it may be prefe zble to connect .
I
~l~ZZ90~3 metal cap members 70 and 70~ ~o the carbon disc through pins 104 and 105 whish extend through the cer,ter of side walls 74 and 76, and the splines 62 and side walls 74n and 76 and splines 62~, By locating the pins 104 and 105 in the center of 5pl ines 62 and 62n, any expansion changes in the metal cap me~bers 70 and 70~ with respect to splines 62 and 62n should not introduce any additional stresses on either the metal caps 7~, 70~ 70n or the splines 62, 62',..62n since the side wall 74, 74'...74~ and 76, 76'...76" should expand equally around the pins 104 and 105 Thus, even though tabs 84 and 82~ are not welded together, a ~ubstantially continuous ring of protection from direct exposure to the oxygen in the air is provided.
MODE OF OPERATION OF THE INVE~ITION
-When the tire on wheel 10 engages the grour,d and the aircraft is moving,wheel 10 rotates. Since rotors 50 are connected to wheel lC, they also rotate while stators 52 remain stationary with respect to axle 12. To effect a brake application, a pilot activates a fluid pressure source (not shown) which is communicated through conduit 23 to piston 24, This fluid pressure acts on piston 24 and provides an axial.force which moves pressure plate 54 toward backing plate 46 to bring the rotors 5~ and stators 52 into frictional engagement This frictional engagement generates thermal energy in the carbon disc of each of the rotors 50 and statcrs 52, The swept section of stators 52, illus~rated by line 9C In Figure 2, is protected from oxidation caused by oxygen in the presence of high thermal energy through the engagement of the adjacent rotor 50. That portion of the splines 62 and root section 71 in the swept section are protected by !egs 78 and 80 and tabs 82 and 8~ of the cap members that extend into the swept section of the brake assembly.
âimilarly, the splines of the rotors 5a are also protected by cap member 70. After a repeated number of brake applicatio~s, the rotors and stators wear, however, as sho~n Tn Figure 5, the oxidation protect;on ring 3o for that portion of the splines 62 outside of the s~ept sectlGn remains ~z~o~
since the carbon material on the adjacent rotors engage legs 73 and 80 and tabs 82 and 84 ~o w~ar away a portion of the protection ring at a rate corresponding to the wear rate of adjacent. rotor and stator carbon friction discs~ As shown in Figure 5> peripheral surface 92 and 92' on rotors 50 and 5G' establish an effective sealing surface with surfaces 9~ and 94' on splines 62 to maintain the structural unity of the carbon friction discs.
For some appllcations it may be desirable that parallel side walls 74 and 76 of the cap members 70 extend into the swept section of the brake.
In order to prevent the adjacent carbon rotors 50 and 50' from wearing the side walls 74 and 76, a protective abras;ve coating such as aluminum oxide;
silicon carbide; industrial diamond~ etc., is applied to selected portions lQ0 and 1~2 of side walls 74 and 76, as shown in Figure 6. Thereafter, as the carbon rotors and sta~ors wear, the abrasive surfaces lOC and 102 eng2ge a;l arcuate segment of peripheral surface 107 and lQ6, see fig~re 7, ~n the adjacent carbon disc to maintain the air restrictive seal ,or the continuous ring of protection, It has been determined that the temperature at the interface between the swept section and the non-swept section of each carbon friction disc can often reach 400C. Even though the carbon friction disc and the protecti~
metal cap members 70, 70'.. ~70n have different coefficients of expansion, the carbon splines 62, 621,..62~l are not damaged since the slde walls 74 and 76 can rnove independently of legs 78 and 80, That portion of the legs 78 and 8~
and the tabs 82 and 84 which are located in the swept section of the friction disc are subjected to the maximum thermal energy generated during a hrake application. As shown in Ftgure ~, a certain amount of clearance is present between the first tabs 82~ 82~ and the ~-oot sect;ons 71, 71',,,71n, The thickness of the first tabs 82, 82n is such that this clearance allo~s the protective ring to expand without damaging the carbon spl;nes 62, 621,,,62~
or the protective ring whenever the temperature is sufficient to expand tne metal cap members 70, 70n, After repeated brake applications, the carbon disc in the rotors and stators a'e worn and must be replaced in order to have adequate braking since the stroke of piston 24 is limited to a fixed distance. When this stroke limit is reached, the rotors and stators are removed from the brake. However, the metal cap members as shown in figure 6 are salvageable since the abrasive coating wears the carbon disc rather than the metal being worn away. Thereafter, the first pin 104 and a second pin 105 are removed from the center of the side walls 74 and 76 on adjacent metal caps 7û and 70n When pins 104 and 105 are removed, the flexibility of the protecti~le ring through the welded connections between the tabs 82 and 84 Of the remaining metal cap members 70 is such that the C3pS are easily removed from the splines of the worn carbon disc and replaced on a new carbon friction disc by pins 104 and 105.
The use of carbon discs as a friction element in aircraft ~heel and brake assemblies have gained acceptance as a way of increasing the payload of an aircraft by reducing the weight of braking systems.
In U.S. Patent No. 3,639,197, it is disclosed how a continuous carbon fiber can provide a carbon disc with the structural unity needed to absorb repeated braking torque. Such carbon friction disc when used in aircraft braking systems often experience thermal conditions above 800F. Above 800F the non-swept areas of the carbon friction disc are subject to accelerated oxidation which can lead to a disintegration of the carbon matrix and continuous carbon fiber resulting in a brake element failure.
In U.S. Patent No. 3,914, 508 a method is disclosed for protecting a carbon substrate in a moist environment from oxidation by coating a selected surface thereof with a boron and metallic mixture attached thereto by a resin matrix. As with most coatings, it is difficult to maintain a uniform thickness over the entire peripheral surface.
As a result where the coating is limited or absent, deterioration of the carbon substrate often takes place after repeated applications.
In a further attempt to protect a carbon friction material, a metal ring as disclosed in U.S. Patent 3,473,637, was placed on the outer periphery of a carbon disc to prevent oxidation of the non-swept area. During frictional operation when the thermal energy produced is low, such protection is effective. However, as the thermal energy generated during braking increases, the unity of the carbon material and steel ring change in a direct proportion to the differences in their thermal coefficients of expansion. After a repeated ~.a - 1 - ~ ~
l~ZZ908 number of frictiona] cnga~ements at high teml)eratures, structural defects can occur along the peripllcry of the carbon material because of different coefficients of expansion. Thereafter, oxygen in the surrounding air can enter and degrade the underlying carbon friction disc.
U.S. Patent 3,9~2,395 discloses a protection member which matches the coefficient of thermal expansion of the carbon friction disc. The protection member, which includes a woven carbon sheath and a protecting screen, is bonded to the peripheral non-swept surface to protect the underlying carbon friction disc. In order to protect the driving slots on the rotor member, a reinforcing plate is attached to the peripheral surface by a driving pin that extends through the carbon friction disc. Unfortunately, the driving pins are located in a high stress area and under some extreme conditions a structural failure may occur in the area of the driving pins.
The present invention resides in a wheel and brake assembly having a key slot coupling through which a plurality of carbon friction discs are moved toward each other during a brake application by an actuator to develop a braking torque, each of the carbon friction dlscs having a series of splines separated by root sectlon, the splines and root sections being protected by cover means to reduce degradation of the carbon friction discs by an oxidizing atmosphere.
In the present invention the cover means extends into the root sections and engage adjacent carbon friction discs on each brake application to maintain the protection after repeated brake applications.
In a specific embodiment of the invention the cover means includes a series of cap members which surround a corresponding series of driving splines to protect the underlying carbon material from degradation through oxidation.
Each of the cap members have a portion thereof that extencl into swept areas of the carbon ~riction disc, and first and second tabs that project into the root sections between the driving splines. The first tab on a cap is fixed to a second tab on an adjacent cap to hold the caps tight against the splines and thereby establisll a continuous ring of protection against oxidation for the carbon friction disc.
During a brake application, the carbon friction disc adjacent the series of cap members engage a portion of each cap member and provide a positive seal from an oxidation atmosphere for the non-swept portion of the carbon friction disc. As the carbon friction discs wear, either that portion of the cap members in the swept area or the adjacent carbon friction discs wear to maintain the positive seal of protection after repeated brake applications.
It is an object of this invention to provide a carbon friction disc in a wheel and brake system with a series of cap members to protect the driving splines and root sections from oxidation during a brake application.
~zz908 It is another object of this invention to provide a carbon frictiGn disc ~ith a series cf ~etal cap members for surrounding a corresponding sertes o~ driving ~lines.
It is a further object of this ;nvention to provide a relatively fle~ible metallic mo~ber for protecting a peripheral surface of a carbon friction disc and thereby reduce the possibility of degradation thereof in an oxidi~ing atmosphere.
These and other obiects should be apparent from reading this specification and viewing the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is 3 sectiona; view of an aircraft wheel and brake assembly having a plurality carbon fr;ction disc with protection caps made according to this invention to reduce degradation of the carbon friction disc when exposed to an oxidizing atmosphere;
Figure 2 is a perspective vie~w of a segment of the carban frlction disc of Figure 1 having protection caps located on the drtving splines;
Figure 3 is a sectional view taken along ltne 3-3 of Figure 2;
Figure 4 is a perspective view of a single protectton cap;
Figure 5 is a sectional view of a segment of a carbon frlction disc taken along lines 5-5 of Figure 2 sho~lng the relationships of a protection cap and the peripheral surface of adjacont carbon friction discs after repeated brake applications;
Fi~ure 6 is a sectional view of a segment of a c~rbon disc having a pro-tection cap wlth an abrasive surface engaged wlth the per;pheral surface of adjacent carbon friction discs; and Figure 7 is a sectlonal vie~ of the carbon friction disc of Fi~ure 6 after a predetermined number of brake applications~
~A
DETAILED DESCfilPTION OF THE I~VENTIC~!
The ~heel and brake assembly showr) In Figure l includes a ~heel lO, only partially sho~n that is rotatably mounted sn a stationary axle 12 and a brake 15 ~hat is m~unted on a stationary carrier member 14 fixed to the axle ll by locating pin 12ain slots 18 and 25, Since the structure For rotatably mounting ~heel l~ to axle 12 an~ fi,~ing the stationary carrier member 14 to the axle 12 is well known, rur~her description thereof is not deemed to be n~cessary.
The wheel 10 has a first section 32 th3t includes a hub 36 and a rim 38 interconnected to each other by a plura!ity of spokes 40 and a secor,d sect;on 34, The first and second sections 32 and 34 are joir,ed tosether by a plurality of bolts 31 after a tire is mour.~ed on the whe~l lO, The carrier member l4 contains a plurality o~ fluid motors 15 (only one is shown in Figure l) which are connected to a fluid pressure scurce ~hrough conduit 23, ach fluid motor 15 has a piston 24 located in a bare 22 that moves a pressure plate 46 toward a backing plate 48 in response to a brake actuation signal in the form of an increase in fluid pressure transmitted through conduit 23 to actuation chamber 30. The back;ng plate 48 ts connected to a flange 42 which radially projects from sleeve 44 which Is secured to the carrier member l4 by a plurality of circumferentially spaced boits 48, The disc brake lllus~rated in Figure l includes a plurality of interleaved rotors 5~, ~shich are splined to and are rotated by the alrcraft wheel 10 and a plurality of statcrs 52, which are splined to sle~e 44 o, the torque tu~e, 80th the rotors and --tators are ~ovable a,xially by piston 24 and are sor~times referred t;a as a brake ~stack~I, rhe pressure plat~ 46, ~hich is attached to piston 24 of the .^lui~ mo.or 16 hasa carbor. friction pad ~;hich acts on and forces the rotors 50 ard statOrs 52 against each other ar.d the entire stack against a carbon ~5-ll'~Z908 friction pad on the backing plate 48~ It is the frictional engagement of the rotatable rotors 50 with the stationary stators 52 which produce the brak;ng actlon of the aircraft ~heel<
Du,ing a brake application, the .emperature generated by the frictional en~agement of the swept sections, illustrated by dashed line 90 in figure 2, of the carbon friction rotors and stators can often reach 500 C.
This temperature wl1ich is carried into the non-swept sections, such as the dr;ving splines 60, 60', 60", and 62, 62', and root sections 71, 71'...71~
separating the splines, could cause the carbon to combine with oxygen n the o air of the surrounding envtronment an~degrade the driving splines. However, a series of cap members 70, 70~...70n, as best shown in ~igures 2 and 4 foFm a continuous rtng of pro.ection for the splines 62 and root section 71 to restrict oxygen from directly contacting the carbon friction rotors and stators 52.
~ ach of the cap members 70 as shown in fjgures 2, 3 and 4 have a base 72 with parallel side walls 74 and 76 and first and second !egs 78 and 80 which extend therefrom. A first tab 82 projects from the ~irst leg 78 and a second tab 84 projects from the seGond leg 80~ The first tab 82 of a first metal cap member 70 is aligned t~ith a second tab 84' of a second cap member 70' and secured together through spot or projection ~elds. Thereafter, the first tab 84' of cap member 70' i5 aligned and welded to the second tab 84" of a me~al cap member 70". This alignment and welding continues until met~i cap member 70n is reached ~ith only the second tab 84 and the first tab 82~
remaining unattached to each other, Thereafter, hase 72 on the first metal cap member 70 is positioned on the top of a spline 62 ~tth tab 84 on leg 80 flush wi~h root section 71. The remaining metal cap member 70~ .,7Qn are positioned on splines 62I...62~ until the f;rst tab 82~ js aligned ~it~ t~e second tah 84 on czp member 7a. As ~hown in Figure 2, tah 82~ laps o~eI the end cf t~b 84 Thereafter, tabs 84 and S2~ can be connected together by a single spot ~eld to establish a continucus ring. ~cwever, it may be prefe zble to connect .
I
~l~ZZ90~3 metal cap members 70 and 70~ ~o the carbon disc through pins 104 and 105 whish extend through the cer,ter of side walls 74 and 76, and the splines 62 and side walls 74n and 76 and splines 62~, By locating the pins 104 and 105 in the center of 5pl ines 62 and 62n, any expansion changes in the metal cap me~bers 70 and 70~ with respect to splines 62 and 62n should not introduce any additional stresses on either the metal caps 7~, 70~ 70n or the splines 62, 62',..62n since the side wall 74, 74'...74~ and 76, 76'...76" should expand equally around the pins 104 and 105 Thus, even though tabs 84 and 82~ are not welded together, a ~ubstantially continuous ring of protection from direct exposure to the oxygen in the air is provided.
MODE OF OPERATION OF THE INVE~ITION
-When the tire on wheel 10 engages the grour,d and the aircraft is moving,wheel 10 rotates. Since rotors 50 are connected to wheel lC, they also rotate while stators 52 remain stationary with respect to axle 12. To effect a brake application, a pilot activates a fluid pressure source (not shown) which is communicated through conduit 23 to piston 24, This fluid pressure acts on piston 24 and provides an axial.force which moves pressure plate 54 toward backing plate 46 to bring the rotors 5~ and stators 52 into frictional engagement This frictional engagement generates thermal energy in the carbon disc of each of the rotors 50 and statcrs 52, The swept section of stators 52, illus~rated by line 9C In Figure 2, is protected from oxidation caused by oxygen in the presence of high thermal energy through the engagement of the adjacent rotor 50. That portion of the splines 62 and root section 71 in the swept section are protected by !egs 78 and 80 and tabs 82 and 8~ of the cap members that extend into the swept section of the brake assembly.
âimilarly, the splines of the rotors 5a are also protected by cap member 70. After a repeated number of brake applicatio~s, the rotors and stators wear, however, as sho~n Tn Figure 5, the oxidation protect;on ring 3o for that portion of the splines 62 outside of the s~ept sectlGn remains ~z~o~
since the carbon material on the adjacent rotors engage legs 73 and 80 and tabs 82 and 84 ~o w~ar away a portion of the protection ring at a rate corresponding to the wear rate of adjacent. rotor and stator carbon friction discs~ As shown in Figure 5> peripheral surface 92 and 92' on rotors 50 and 5G' establish an effective sealing surface with surfaces 9~ and 94' on splines 62 to maintain the structural unity of the carbon friction discs.
For some appllcations it may be desirable that parallel side walls 74 and 76 of the cap members 70 extend into the swept section of the brake.
In order to prevent the adjacent carbon rotors 50 and 50' from wearing the side walls 74 and 76, a protective abras;ve coating such as aluminum oxide;
silicon carbide; industrial diamond~ etc., is applied to selected portions lQ0 and 1~2 of side walls 74 and 76, as shown in Figure 6. Thereafter, as the carbon rotors and sta~ors wear, the abrasive surfaces lOC and 102 eng2ge a;l arcuate segment of peripheral surface 107 and lQ6, see fig~re 7, ~n the adjacent carbon disc to maintain the air restrictive seal ,or the continuous ring of protection, It has been determined that the temperature at the interface between the swept section and the non-swept section of each carbon friction disc can often reach 400C. Even though the carbon friction disc and the protecti~
metal cap members 70, 70'.. ~70n have different coefficients of expansion, the carbon splines 62, 621,..62~l are not damaged since the slde walls 74 and 76 can rnove independently of legs 78 and 80, That portion of the legs 78 and 8~
and the tabs 82 and 84 which are located in the swept section of the friction disc are subjected to the maximum thermal energy generated during a hrake application. As shown in Ftgure ~, a certain amount of clearance is present between the first tabs 82~ 82~ and the ~-oot sect;ons 71, 71',,,71n, The thickness of the first tabs 82, 82n is such that this clearance allo~s the protective ring to expand without damaging the carbon spl;nes 62, 621,,,62~
or the protective ring whenever the temperature is sufficient to expand tne metal cap members 70, 70n, After repeated brake applications, the carbon disc in the rotors and stators a'e worn and must be replaced in order to have adequate braking since the stroke of piston 24 is limited to a fixed distance. When this stroke limit is reached, the rotors and stators are removed from the brake. However, the metal cap members as shown in figure 6 are salvageable since the abrasive coating wears the carbon disc rather than the metal being worn away. Thereafter, the first pin 104 and a second pin 105 are removed from the center of the side walls 74 and 76 on adjacent metal caps 7û and 70n When pins 104 and 105 are removed, the flexibility of the protecti~le ring through the welded connections between the tabs 82 and 84 Of the remaining metal cap members 70 is such that the C3pS are easily removed from the splines of the worn carbon disc and replaced on a new carbon friction disc by pins 104 and 105.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a wheel and brake assembly having a key slot coupling through which a plurality of carbon friction discs are moved toward each other during a brake application by an actuator to develop a braking torque, each of said carbon friction discs having a series of splines separated by root sections, said splines and root sections being protected by cover means to reduce degradation of the carbon friction discs by an oxidizing atmosphere, the improvement wherein said cover means extend into said root sections and engage adjacent carbon friction discs on each brake application to maintain said protection after repeated brake applications.
2. In the wheel and brake assembly, as recited in claim 1 wherein said cover means includes:
a series of cap members that surround said splines, each cap in said series of cap members having a first tab and a second tab that projects into said root sections, a first tab on a cap member and a second tab on an adjacent cap being fixed to each other to establish a continuous ring of protection for both the splines and root sections of said carbon friction disc.
a series of cap members that surround said splines, each cap in said series of cap members having a first tab and a second tab that projects into said root sections, a first tab on a cap member and a second tab on an adjacent cap being fixed to each other to establish a continuous ring of protection for both the splines and root sections of said carbon friction disc.
3. In the wheel and brake assembly, as recited in claim 2 wherein each of said cap members include:
first and second abrasive surfaces for engaging adjacent carbon friction discs to prevent said adjacent carbon friction discs from wearing away said cap members and thereby exposing said carbon friction discs to the oxidizing atmosphere.
first and second abrasive surfaces for engaging adjacent carbon friction discs to prevent said adjacent carbon friction discs from wearing away said cap members and thereby exposing said carbon friction discs to the oxidizing atmosphere.
4. In the wheel and brake assembly, as recited in claim 2 wherein a portion of each of said cap members is progressively worn by repeated engagements with said adjacent carbon friction discs to restrict the communication of air between the peripheral surfaces of the adjacent carbon friction discs and said splines.
5. In the wheel and brake assembly as recited in claim 4 further including:
a plurality of pins extending through a portion of said cap members to retain said cap members against said carbon friction discs after a repeated number of brake applications.
a plurality of pins extending through a portion of said cap members to retain said cap members against said carbon friction discs after a repeated number of brake applications.
6. In the wheel and brake assembly, as recited in claim 2 wherein said cap members are only attached to each other through the first and second tabs on adjacent caps.
7. In the wheel and brake assembly as recited in claim 6 wherein said first and second tabs can expand within said root section without damaging the splines.
8. In a wheel and brake assembly having a key-slot coupling through which a braking torque is transmitted during engagement of a plurality of carbon friction discs to effect a brake application, each of said carbon friction discs having a series of splines that extend from a swept section to a non-swept section, each spline in said series of splines being separated from each other by a root section, said non-swept section and each root section being subjected to an oxidizing environment that could structurally degrade said carbon friction disc, the improvement comprising:
a series of caps surrounding that portion of series of splines in the non-swept section of said carbon friction disc, each cap in said series of caps having first and second tabs extending into root sections on opposite sides of each spline, said first tab on each cap and a second tab on an adjacent cap being attached to each other to establish a continuous ring of protection to prevent said carbon friction disc from being directly exposed to said oxidizing environment, said first and second tabs on each cap of said series of caps extend into said swept section of said cap friction disc, said first and second tabs and carbon friction discs in said swept section being worn through the engagement with adjacent carbon friction discs to assure that said series of splines remain protected from the oxidizing environment after repeated brake applications.
a series of caps surrounding that portion of series of splines in the non-swept section of said carbon friction disc, each cap in said series of caps having first and second tabs extending into root sections on opposite sides of each spline, said first tab on each cap and a second tab on an adjacent cap being attached to each other to establish a continuous ring of protection to prevent said carbon friction disc from being directly exposed to said oxidizing environment, said first and second tabs on each cap of said series of caps extend into said swept section of said cap friction disc, said first and second tabs and carbon friction discs in said swept section being worn through the engagement with adjacent carbon friction discs to assure that said series of splines remain protected from the oxidizing environment after repeated brake applications.
9. In the wheel and brake assembly, as recited in claim 8 wherein that portion of the series of caps that extend into said swept section of said carbon friction discs each have an abrasive surface thereon which engage an adjacent carbon friction disc, said abrasive surface wearing said adjacent carbon friction disc to prevent structural damage to said series of caps after repeated brake applications.
10. In the wheel and brake assembly, as recited in claim 8, further including:
pins extending through a selected member of said series of caps to positively retain each of said caps against the non-swept section of said carbon friction discs.
pins extending through a selected member of said series of caps to positively retain each of said caps against the non-swept section of said carbon friction discs.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US958,213 | 1978-11-06 | ||
| US05/958,213 US4249642A (en) | 1978-11-06 | 1978-11-06 | Oxidation inhibiting cap for a carbon friction disc |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122908A true CA1122908A (en) | 1982-05-04 |
Family
ID=25500730
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA337,961A Expired CA1122908A (en) | 1978-11-06 | 1979-10-18 | Oxidation inhibiting cap for a carbon friction disc |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4249642A (en) |
| JP (1) | JPS5569333A (en) |
| CA (1) | CA1122908A (en) |
| DE (1) | DE2944793A1 (en) |
| FR (1) | FR2441099A1 (en) |
| GB (1) | GB2034835B (en) |
| IT (1) | IT1124902B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4469204A (en) * | 1983-01-28 | 1984-09-04 | The B. F. Goodrich Company | Brake apparatus |
| US4465165A (en) * | 1983-01-28 | 1984-08-14 | The B. F. Goodrich Company | Brake apparatus |
| US4511021A (en) * | 1983-04-21 | 1985-04-16 | The B. F. Goodrich Company | Brake apparatus |
| US4557356A (en) * | 1984-04-30 | 1985-12-10 | Goodyear Aerospace Corporation | Brake disk and keyslot reinforcements therefor |
| EP0235011B1 (en) * | 1986-02-05 | 1990-05-02 | Societe Europeenne De Propulsion | Friction system using composite refractory materials |
| US4863001A (en) * | 1987-02-18 | 1989-09-05 | The Bf Goodrich Company | Brake apparatus |
| US4815572A (en) * | 1987-07-24 | 1989-03-28 | Parker-Hannifin Corporation | Brake system with improved brake material |
| USRE36363E (en) * | 1987-11-27 | 1999-11-02 | Tilton Engineering | Carbon to carbon friction clutch |
| US4844206A (en) * | 1987-12-18 | 1989-07-04 | Allied-Signal Inc. | Dual disk brake |
| DE69332562T2 (en) * | 1992-08-13 | 2003-07-10 | Tilton Engineering, Inc. | CARBON CARBON FRICTION MECHANISM |
| US20080041674A1 (en) * | 2006-08-18 | 2008-02-21 | Honeywell International Inc. | Carbon-carbon stator insert for aircraft brakes |
| GB2550364A (en) * | 2016-05-16 | 2017-11-22 | Airbus Operations Ltd | Aircraft brake temperature measurement |
| EP3753793B1 (en) * | 2019-06-21 | 2023-02-22 | Goodrich Corporation | Braking system for an aircraft wheel |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3757907A (en) * | 1971-05-24 | 1973-09-11 | Goodyear Tire & Rubber | Key slot segments for driving brake discs |
| US3927740A (en) * | 1974-07-01 | 1975-12-23 | Goodyear Aerospace Corp | Brake disk with tapered key way |
| US4083434A (en) * | 1976-04-26 | 1978-04-11 | Pinter Henry J | Brake disc with anti-oxidation peripheral covering |
-
1978
- 1978-11-06 US US05/958,213 patent/US4249642A/en not_active Expired - Lifetime
-
1979
- 1979-10-18 GB GB7936261A patent/GB2034835B/en not_active Expired
- 1979-10-18 CA CA337,961A patent/CA1122908A/en not_active Expired
- 1979-11-02 IT IT27006/79A patent/IT1124902B/en active
- 1979-11-05 JP JP14316379A patent/JPS5569333A/en active Pending
- 1979-11-05 FR FR7927213A patent/FR2441099A1/en active Granted
- 1979-11-06 DE DE19792944793 patent/DE2944793A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2034835B (en) | 1983-05-05 |
| GB2034835A (en) | 1980-06-11 |
| IT1124902B (en) | 1986-05-14 |
| FR2441099B1 (en) | 1982-04-16 |
| DE2944793A1 (en) | 1980-05-14 |
| FR2441099A1 (en) | 1980-06-06 |
| US4249642A (en) | 1981-02-10 |
| IT7927006A0 (en) | 1979-11-02 |
| JPS5569333A (en) | 1980-05-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |